In oxide removal processes, such as HF treatment for patterning oxide layers in dual gate oxide integration, silicon surfaces exposed by the HF treatment are rendered hydrophobic and made more prone to particle contamination. This observation may, in part, be evidenced by the lack of substrate wetting coverage, when for example, rinsing with aqueous media in the subsequent ViPR™ resist removal step that may be performed using the ORION® single wafer processing tool commercially available from TEL FSI, Inc. (Chaska, Minn.). Additional details for resist removal using point-of-use mixing of steam (water vapor) and SPM (sulfuric acid-hydrogen peroxide mixture), such as the ViPR™ process, are provided in U.S. Patent Application Publication No. 2010/0018951, entitled “Process for removing material from substrates”, the content of which is incorporated herein by reference in its entirety.
In a conventional process, an oxide layer is patterned by exposing the oxide layer to an HF solution through a patterned mask layer, such as a layer of photoresist having a pattern formed therein using a lithographic process. Thereafter, the patterned mask layer is removed by exposure to SPM (sulfuric acid-hydrogen peroxide mixture), such as a ViPR™ process, followed by exposure to a cleaning process for removing particles that includes exposure to an aqueous solution of ammonium hydroxide and hydrogen peroxide. Following the HF treatment, some exposed surfaces on the substrate may be made hydrophobic, and thus, be prone to particle contamination. And, such particle contamination may be exacerbated when the substrate fails to be continuously wetted from the HF treatment step through the patterned mask layer removal step.